Process of preparing 1-phenyl-3-methyl-5-pyrazolone



Patented Aug. 6, 1929.

UNITED STATES.

PATENT OFFICE.

HANS FINKELS'IEIN AND HANS HKUBER, OF UERDINGEN, GERMANY, ASSIGNORS TO I.- G. FABBENINDUSTRIE AKTIENGESELLSCHAFT, 0F FRANKFORT-ON IHE-MAIN, I Gil?IRQIVIANY, A CORPORATION OF GERMANY.

rnocrzss or PREPARING 1-PHENYL-3-MEIHYL-5-E'YRAZOLONE.

No Drawing. Application filed February 10, 1927, Serial No. 167,349, and in Germany October 21, 1925.

It is already known to oxidize phenylmethylpyrazolidone in an alcoholic solution with ferric chloride to the corresponding yrazolone. It is also known to prepare l-p 1enyl-5-pyrazolone-3-carboxylic acid by 0x1- dizing the corresponding pyrazolidone carboxylic acid by means of ferric chloride 1n an aqueous solution.

Now we have found that when using an aqueous hydrochloride solution and oxygen or an oxygen-containing gas as oxidizing agent, the oxidation can be effected in an excellent manner by adding to the compounds as catalysts salts of the heavy metals capable of acting as oxygen-carriers.

The reaction probably takes lace in two phases which may be illustrate by the following two equations:

The following example serves to illustrate our invention, but it is not intended to limit ably under a somewhat increased pressure, until the required quantity of oxygen has been absorbed by the liquid. Already .during the passage of the air through the solution crystals of phenylmethylpyrazolone hydrochloride are precipitated. When the introduction of oxygen is complete, the crystallization process is accelerated by cooling the liquid to about 5 C. In this manner 25 kg. of the hydrochloride are obtained. After the quantities of phenylmethylpyrazolidone and hydrochloric acid consumed have been reintroduced, the mother liquor may be employed for a new oxidation process without adding r a further'quantity of the catalyst. By a number of operations following each other in the manner above indicated the pyrazolone derivative is obtained with an almost quantitative yield.

We claim:

1. Process for the production of 1-phenyl-3-Inethyl-5-piyrazolone, which comprises treating l-pheny -3-metliyl-5-pyrazolidone in an aqueous solution of hydrochloric acid with oxygen in the presence of a copper salt capable of acting as oxygen-carrier.

2. Process for the production ofl-phenyl- 3-1nethyl-5pyrazolone, which comprises treating 1-phenyl-3-methyl-5-pyrazolidone in an aqueous solution of hydrochloric acid wiith oxygen in the presence of copper chlor1 e.

In testimony whereof, we afiix our signa- HANS FI NKELSTEIN. HANS HAUBER.

' tures. 

